A computer-controlled 100 Channel High Speed Spectrophotometer is being developed by the Biomedical Engineering and Instrumentation Program of the National Center for Research Resources and CSL for the Laboratory of Cell Biology, NHLBI. It will be used to obtain more complete spectral information concerning the rapid changes of the reduction and oxidation centers within the protein enzyme cytochrome oxidase. This enzyme is involved in cellular respiration and is located within the inner lipid bilayer of the mitochondria. CSL has assisted in defining the interface between the diode array spectrophotometer and the computer, and has developed the data acquisition and control software. The researcher intends to use the modeling program MLAB to analyze the data. BEIP has designed, built, and , with the assistance of CSL, tested a prototype eight-channel interface board with one analog to digital converter and its associated 1024 words of high speed memory per input. Subsequently, they arranged for this design to be fabricated in a printed circuit boards. A "mother board" capable of accepting and controlling twelve interface boards has also been fabricated as a printed circuit. The spectrophotometer is in a similar stage of fabrication. CSL is working with BEIP on a daily basis to assemble and test the complete interface.